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So cold, boiling water turns to snow

With temperatures across the United States as low as minus 41 degrees, boiling water thrown into the air is turning into snow. ANU physical chemist, Denis Evans, explains why it happens. Pic: Eric Holthaus

As one of the coldest weather fronts in decades cancelled flights and closed schools in the United States, one Wisconsin man took to the outdoors armed with a saucepan to show the world just how cold it was in his backyard.

Braving temperatures around minus 30 degrees, before the wind chill, meteorologist Eric Holthaus said he wanted to examine whether he could create instant snow out of boiling water, as other videos on YouTube seemed to suggest.

But his doubts were misplaced. A video uploaded to YouTube shows Holthaus throw take a pot of boiling water out into his garden, where the temperature is minus 29 degrees with a wind chill of minus 46 degrees. The water flies into the air, surrounded by steam, before some falls back to Earth as snow.

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Australian National University Professor Denis Evans said when temperatures were cold enough, vapour from boiling water becomes supercooled and freezes instantly when it makes contact with the air.

“If the temp wasn’t so cold, that vapour would just produce a water fog. But at minus 40 degrees, that vapour freezes into an ice fog,”

Meteorologist Eric Holthaus prepares to head out into the cold with a pot of steaming water.

When water particles are large droplets, like water thrown from a pot, the particles will turn to ice more easily, Professor Evans said.

However, the smaller water droplets in the spray or steam are very fine diameter particles, which will turn into delicate crystal forms and settle like ordinary snow fall.

Any Australians hoping to replicate the trick, however, will need to buy a plane ticket.

“It will never get that cold in Australia,” Professor Evans said.

The bitter cold that has spread over the United States in the past week is the result of an Arctic polar vortex reaching further south than usual, blasting Arctic air into the country.

‘‘This is a particularly dangerous situation,” the National Weather Service has warned.

“Temperatures this cold present a potentially life threatening situation if outdoors.”

The weather front is being hailed as the worst cold outbreak in almost 20 years. The weather service says dangerously cold wind chill, as low as minus 51 degrees, is set to hit the northern centre of the country on Tuesday and move towards the eastern seaboard.

Temperatures across parts of the upper mid-west have reportedly reached as low as minus 40 degrees.

‘‘I am sure there are going to be multiple records broken across a large part of the country,” meteorologist Mat Musher told The New York Times.

‘‘Everybody’s energy bills will be going up.”’

In Minnesota and Chicago, all public schools have been closed, with governors saying it would be too dangerous for children to commute to school in sub-zero temperatures and high winds.

More than 4000 flights have been cancelled in the past 24 hours around the country, according to flight tracking service FlightAware.

On Sunday, freezing temperatures and icy runways in New York are believed to have caused a plane at New York’s Kennedy International Airport to slide into a snowbank after landing.

In another video taken in Canada last week, a man sprays boiling water from a toy water gun, which turns into a stream of snow. The temperature was at least minus 40 degrees.